Ventilating indoor garden with flowering tent & room and vegetative area as well

Ventilating indoor garden with flowering tent & room and vegetative area as well

Have a complicated situation requiring ventilation of 4' x 4' x 7' flowering tent within utility room measuring 12' 8" x 9' 9" with ceiling on 8' one end x 11' on other end giving roughly 1174 cubic feet including space within flowering tent. Room contains vegetative section as well as gas boiler for sub flooring heat & hot water. Also gas dryer and washer occupy this space. Have 424 CFM fan for exchanging stale air for fresh air. Currently door not installed but for safety when door installed 6" air inlet to outside required and outlet to vent air outside to provide safety for possible gas leak and also to provide garden with continuous fresh air. Carbon filter installed inside tent to filter out impurities, odor, microbes and fungi. My question is how to utilize fan to filter entire room including tent and not draw in excess cold air in winter. While still being able to keep door closed most of time. Have fan speed controller and one idea I have come up with is using a Y to split light weight duct work outside of tent and possibly a damper of some sort to balance airflow going from tent and room to outside vent. The fan & ductwork is 6" and other vents are available to draw air into tent and filter it there. If anyone has ideas and/or calculations to utilize for this project I would greatly appreciate any feedback. This is the first time I have attempted a project like this. Thanks!

Whatcha growing? How much lighting and what type are in the grow tent? Will you have to provide cooling air for the lights?

I am curious why you want to filter the main room air. I'm even curious why you are filtering the air inside the greenhouse. What plants need such pure air?

I would treat the air filtering and exchanging fresh air as two separate issues. Maybe a filtration unit that you can plumb as needed, splitting it's output between the main room and greenhouse. Then a separate fan or blower to bring in fresh air from the outside as needed. You could size the ventilation fan so it runs continuously to provide the air needed or you could control the vent fan with a thermostat or timer to limit the amount of outside are you bring inside.

Gas leaking from the boiler or other appliance will collect at the floor. You will need a fan sucking in air down at floor level to evacuate it or provide enough ventilation to stir up the room. Your big concern should be pressurizing or drawing a vacuum in the room. Keep in mind that the boiler's flue and dryer's exhaust line are also ventilation ducts to the outside. Circulating air within the room should not be a problem but power venting air in or out of the room could cause problems with the combustion gases venting up the flue. Your ventilation system could inadvertently suck noxious gases back into the room.